Low Power Conditions Research Articles

Higher-Order Optomechanical Nonlinearity Based on the Mechanical Effect of Light

Nonlinear cavity optomechanics based on the mechanical effect of light has recently received considerable attention due to its potential applications in high-precision metrology. In this work, we theoretically studied the third-order optomechanical nonlinearity by using a perturbative approach, and an analytical solution is given, which can be extended to cases of higher-order optomechanical nonlinearity. Furthermore, the generation of a third-order sideband is analyzed in detail, and the results show that the amplitude of the third-order sideband shows a high dependence on the control field detuning, suggesting that the high-order nonlinear intensity can be enhanced by properly adjusting the detuning of the laser field rather than by a strong laser drive. In addition to providing insight into optomechanical nonlinearity, the analytical description of third-order optomechanical nonlinearity based on the mechanical effects of light may find applications in ultra-high precision measurement under low power conditions.

1,4-Bis(trimethylsilyl)piperazine—Thermal Properties and Application as CVD Precursor

We report an investigation into 1,4-Bis-N,N-(trimethylsilyl)piperazine (BTMSP) as a novel precursor for the synthesis of silicon carbonitride films by chemical vapor deposition (CVD). The thermal stability, temperature dependence of vapor pressure and thermodynamic constants of the evaporation process of BTMSP were determined by static tensimetry with a glass membrane zero manometer. The transformation of the compound in low-power (25 W) plasma conditions was investigated by optical emission spectroscopy. It was shown that BTMSP undergoes destruction, accompanied by H and CH elimination and CN formation. SiCN(H) films were deposited in a hot-wall plasma-enhanced CVD reactor. The optical properties of the films were studied by spectral ellipsometry (refractive index: 1.5–2.2; absorption coefficient: 0–0.12) and UV–Vis spectroscopy (transmittance: up to 95%; optical bandgap: 1.6–4.9 eV). Information on the aging behavior of the films is also provided. The transformation of the films occurred through water adsorption and the formation of Si–O bonds with the degradation of Si–H, N–H and Si–CHx–Si bonds.

The effects of fuel distribution on exit temperature distribution in a centrally staged combustor

Fuel injection and distribution play an important role in the formation and migration of hot streaks in gas turbine combustors and determine the exit temperature uniformity especially for modern low emission combustors that have little or no primary and dilution air flows. To better understand the underlying mechanism of the formation and evolution of hot streak, both experimental and numerical investigations have been carried out in a centrally staged tri-sector model combustor. Flow, spray, and flame have been investigated by particle image velocimetry and planar laser-induced fluorescence. The exit temperature distributions are also measured and analyzed with both laser diagnostics and simulation results. The results show that increasing fuel-to-air ratio (FAR) or fuel staging ratio enhances the formation of high temperature hot streak and leads to high overall temperature distribution factor and radial temperature distribution factor at the combustor exit. It is found that the high temperature zone is formed through the non-premixed combustion of pilot stage and resides in the shear layer of pilot stage and primary circulation zone. Increasing FAR at low power conditions and increasing SR at high power conditions promote the formation of a large hot streak area through pilot stage combustion and thus deteriorate the uniformity of temperature distribution at the combustor exit.

Reduction in Submodule Capacitance in FB- and HYB-MMCs With Variable DC Voltages

Full-bridge submodule (FBSM)-based modular multilevel converter (FB-MMC) or hybrid MMC (HYB-MMC) composed of FBSMs and half-bridge submodules are necessary in many applications. However, the arm energy fluctuation during reactive power exchange is very high, causing large sizes and high costs of submodule capacitors. Using the negative states of the FBSMs, the FB-, and HYB-MMCs can dynamically adjust the dc voltage, and this technique has been used in many commissioned projects. This study treats the dc voltage as a new dimension and proposes a new operation mode based on variable dc voltage for FB- or HYB-MMCs to reduce the arm energy fluctuations and submodule capacitance. The basic idea is to reduce the dc voltage in high reactive power and low active power conditions, thereby suppressing the arm energy fluctuations. Theoretical analysis shows that the energy fluctuation and submodule capacitance can be reduced by 30%–40%, and the valve cost can be reduced by 13%. Economic and technical comparison results show that the proposed approach can have similar reduction effects on the capacitance and valve cost, but has fewer technical limits. Simulation and experimental results verify the analysis.

Physics design, fabrication, RF measurement and beam commissioning of a dual beam drift tube linac

A novel type dual-beam drift tube linac (DB-DTL) prototype was firstly designed to prove the feasibility of the multi-beam type DTL at the institute of modern physics. The physics design, cavity fabrication, low-power RF measurement, RF conditioning and beam commissioning of the DB-DTL cavity were completed and presented in this paper. Operating at 81.25 MHz, the DB-DTL was designed to accelerate 10 mA proton from 0.56 MeV to 2.5 MeV. The field distribution of the DB-DTL cavity were measured at low RF power level and particle tracing using measured field were done, which both agree well with the physics design. The measured Q 0 value and the shunt impedance are 11606 and 172 MΩ/m, respectively. The RF conditioning and the first beam commissioning of the DB-DTL cavity were completed. The beam experiment platform was built at the Lanzhou university due to the academy research cooperation between the institute of modern physics, Sun Yat-sen university and Lanzhou university. Based on the existing experiment condition, 2.5 MeV proton acceleration and measurement were successfully achieved at 42 kW (0.85*Q 0)) RF power of the DB-DTL cavity, which match the physics design very well.

Stack cooling system coupled with secondary heat pump in fuel cell electric vehicles

Fuel cell electric vehicles (FCEVs) requires proper thermal management of a proton-exchange membrane fuel cell (PEMFC) stack, but conventional thermal management systems (TMSs) cannot manage the thermal requirements of PEMFCs under high-power density at high ambient temperatures. In this study, a stack cooling system coupled with a secondary heat pump in an FCEV is suggested. The enhanced thermal flexibility of the secondary heat pump system enabled extensive cooling with various TMS configurations. The cooling performance with different TMS configurations was evaluated, considering the thermal and electrical coupling of the heat pump system and the PEMFC stack. The results show that the stack temperature was lowered up to 2.6 °C when the excessive cooling load of the stack radiator was distributed to the cabin radiator under a relatively low-power output condition. To dissipate a large amount of waste heat from the stack, TMS requires a temporary shutdown of the cabin cooling system. In this case, utilizing the inactive outdoor heat exchanger as an additional radiator decreased the temperature up to 18.4 °C by extending the heat transfer area for stack cooling. This study proposes a cooling scheme for an FCEV and suggests appropriate cooling methods and configurations under various operating conditions.

Research on a laboratory monochromatic micro X-ray fluorescence spectrometer based on polycapillary X-ray lenses and flat crystal

Monochromatic micro X-ray fluorescence (Mμ-XRF) analysis has the advantages of high resolution and low detection limit and is a powerful tool to obtain information on element distribution and concentration in materials. An Mμ-XRF spectrometer for laboratory X-ray tubes is developed in this paper, which mainly composed of an X-ray tube, two polycapillary X-ray lenses and a flat crystal. The polycapillary parallel X-ray lens converts the divergent broadband X-rays emitted by the X-ray tube into quasi-parallel X-rays and projects them onto a flat crystal, where monochromatic X-rays are obtained by crystal diffraction. The monochromatic X-rays are then focused by a polycapillary half-focusing X-ray lens to provide spatial resolution for fluorescence analysis. The combination of the two makes it possible to perform Mμ-XRF under laboratory low-power X-ray tube conditions (5.3 W molybdenum tube). By selecting polycapillary half-focusing X-ray lenses with different parameters, the spectrometer can provide a spatial resolution of tens to hundreds of microns to suit various application requirements. The detection limits of the Mμ-XRF spectrometer are also measured using standard solutions. Experimental results show that the detection limit of Se is 52 μg/L and that the detection limit for light elements such as Mn is 970 μg/L.

A combined spectroscopic investigation of cobalt oxide films prepared by DC reactive sputtering

The structure and vibrational characteristics of cobalt monoxide and tetraoxide films, prepared by direct-current DC reactive sputtering, were investigated by different characterization techniques. According to X-ray diffraction analyses, the development of the Co3O4 phase takes place under low discharge power and high substrate temperature (80 W-623 K) conditions, whereas the CoO phase predominates when adopting high discharge power and low substrate temperature (240 W-473 K). Results of infrared absorption and Raman scattering spectroscopies indicate the presence of Co3O4 in all films, that are compatible with the optical transmittance spectra in the UV-Vis-NIR range − showing electronic transitions due to Co2+/3+ cations (related to the Co3O4 spinel structure) in the films deposited at 80 W-623 K and, to a lesser extent, at 240 W-473 K conditions. The investigations include Raman scattering measurements in the 83–623 K range. The results evidence a mixture of phases in the 240 W-473 K film, whose main Raman scattering peaks evolve irreversibly towards Co3O4 upon increasing measurement temperatures. Altogether, the present report provides deeper information about the cobalt oxide phases that shall be useful to improve the control of properties and production of cobalt oxide films by DC reactive sputtering.

Experimental research and theoretical analysis of flow instability in advanced secondary passive residual heat removal system

To cope with station blackout (SBO) accident in the pressurized water reactor (PWR) nuclear power plant (NPP), the advanced secondary passive residual heat removal system (ASP) was developed. A newly advanced secondary passive heat removal system test facility (ASPTF) for generation III NPP was designed and constructed to obtain the thermal hydraulic characteristics of ASP. The flow instability in ASP was observed in ASPTF, which was more likely occurred under low heating power and system pressure conditions. The effects of different influencing factors on flow instability in ASP were obtained. Then, the theoretical analysis of flow instability in ASP was conducted. Based on the experimental and theoretical analysis results, the optimization and improvement measures of ASP were summarized.

Experimental investigation on lean blowout dynamics of spray flame in a multi-swirl staged combustor

• Continuous lean blowout process of spray flames with linear reduction of fuel-to-air ratio. • Evolution of LBO performance under simulated flight-idle conditions inside a staged combustor. • LBO flame dynamics identified by proper orthogonal decomposition method. • Peak frequency transitions can be used as precursors to blowout events. Lean combustion has been widely applied in gas turbine combustors due to its superiority in reducing NOx emissions. However, it poses a significant risk of blowout for aero-engines especially when operating under low power conditions. In this paper, the LBO (lean blowout) process of spray flame was experimentally investigated and the flame was visualized by high-speed imaging of CH* chemiluminescence. A stratified partially premixed injector was applied and fueled with aviation kerosene at simulated flight-idle conditions. During the experiments, LBO was induced through linear reduction of pilot fuel flow rate. It was found that the LBO performances deteriorated as the altitude increases and the relationship between LBO FAR (fuel to air ratio) and altitude conformed to an exponential function. Evolution of flame macrostructures during LBO process showed that the flame changed from a double V-shape to a single V-shape with the decrease of FAR . FFT (fast Fourier transform) and POD (proper orthogonal decomposition) methods were introduced to post-process the high-speed imaging data in different periods before flame extinction. At the last second before LBO, POD modal distributions presented typical axial oscillation, circumferential rotation and high-order radial oscillations successively. The spectral analysis showed that the peak frequencies in the spectra of global CH* chemiluminiscence intensity and the spectra of POD modal time coefficients both changed prominently within 3∼7 seconds before flame complete extinction, which was of good repeatability during repeated tests and was considered to be a precursor for blowout event.

Cascaded Rectifiers for Energy Harvesting With a Wide Dynamic Power Range

This work presents a novel RF energy harvesting system at 2.45 GHz, operating over a wide dynamic RF range (44 dB), starting from ultra-low power. It consists of three rectification branches, each one optimized for a selected power interval, between <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 20\,\,\div \,\,+$ </tex-math></inline-formula> 24 dBm. Through an automatic distribution network, the incident RF power is routed to the most efficient rectification branch, with no need for external control circuits. The first branch is optimized for low-power conditions, in the range <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$- 20\,\,\div \,\,0$ </tex-math></inline-formula> dBm, and the second and third branches for 0 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\div $ </tex-math></inline-formula> 9 dBm and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$9~\div ~24$ </tex-math></inline-formula> dBm, respectively. For branch decoupling, an original strategy, based on the concurrent nonlinear design of power-dependent matching networks and self-powered switches, is used. To maximize each rectifier performance, Enhancement-mode High Electron Mobility transistors (HEMT) are adopted by means of the self-biasing mechanism. In this way, for any possible incoming RF power, only the most suitable rectifier path is active and the maximum RF-to-dc conversion efficiency is preserved. The system has been fabricated and tested demonstrating a conversion efficiency higher than 30% from −13 dBm to 24 dBm, with the lowest and highest measured dc output voltage of 0.1 and 13 V, respectively.

Highly efficient two-step nitrogen doping of graphene oxide-based materials in oxygen presence atmosphere for high-performance transistors and electrochemical applications

Nitrogen content in graphene influences application performance. Although many studies have been conducted on single-process nitrogen (N)-doping, dopant content is still quite low. Therefore, the objective of this study was to develop a novel two-step economical doping technique for improved nitrogen content and device performance. First, graphene oxide (GO) was hydrothermally nitrogen-doped. This nitrogen-doped reduced graphene oxide (NrGO) was then subjected to secondary plasma treatment. Two nitrogen(N)-doping mechanisms were observed depending on graphene’s oxygen functionalized group (OFG) content. OFG assisted N-doping mechanism was dominant if graphene had a high OFG content. Despite the presence of oxygen in plasma, significant OFG reduction and a higher degree of N-doping were observed. On the other hand, if graphene had a low OFG content, activated radicals in graphene structure by plasma ion bombardment mainly influenced secondary N-doping. Here, oxygen contaminants in the plasma stream showed dual effects. Low-power conditions showing no significant effect, whereas high-power plasma influenced re-oxidation and suppressed further N-doping. The maximum N/C ratio of 0.168 was observed in 5 W plasma-treated NrGO material which had nitrogen content over 40%. Compared to a single-step N-doping technique, this new technique can facilitate dominant n-type transistors with strong oxygen reduction characteristics. • The impact of oxygen in plasma depends on OFGs in graphene and plasma power. • Oxygen contaminants can suppress N-doping if graphene has low OFG content. • Oxidized nitrogen formation has no impact by oxygen contaminants in plasma. • Two-step N-doping can provide high N-doping level than single-step doping.

A year-long field investigation on the spatio-temporal variations of occupant's thermal comfort in Chinese traditional courtyard dwellings

Multiple researchers have proven the different thermal perceptions of occupants living in naturally ventilated dwellings. As one of the representatives of Chinese traditional dwellings, courtyard-style vernacular residence is the result of human wisdom in adapting to the natural thermal environment through architectural forms. Exploring whether such classical building form still meets the thermal comfort needs of contemporary residents can help architects generate relevant design concepts when dealing with energy-saving-oriented projects in the context of carbon neutralization and rural revitalization. A year-long follow-up investigation is conducted on a typical courtyard dwelling in Wufu Town, Fujian Province. Based on the built digital twin platform, relevant parameters were monitored by various sensors from different investigation points throughout the year. Additionally, year-round monthly thermally neutral temperatures are obtained from over 1000 Thermal Sensation Vote questionnaires. By applying the adaptive thermal comfort theoretical model, which is widely recognized in the field of thermal assessment on naturally ventilated buildings, the linear relationship between indoor neutral temperature and outdoor air temperature can be generated. According to ASHRAE Standard 55, the time-series predicted acceptable thermal comfort ranges are then calculated to evaluate the measured operative temperature. Results show no large gap between the actual temperature and the predicted acceptable range in semi-open spaces and interior spaces. With suitable optimized renovations and the application of several low-power conditioning equipment, such courtyard dwellings are still capable of providing occupants comfortable thermal environment throughout the year.

Influence of small ground surface on plasma property in an inductively-coupled plasma with floating liner

Currently, the components of semiconductor processing chamber are coated with oxides to avoid metal contamination. As a result, electrical ground is hidden from the plasma. In this study, we experimentally investigate the effect of small ground surfaces in an inductively-coupled plasma (ICP) generated in an electrically floating liner. Peak-to-peak and DC voltages at a biasing stage and a floating liner are measured as a function of stage peak-to-peak voltage for various ICP powers and the ground surface areas. The results show that the stage and liner voltages vary with changing ground surface area due to a change in sheath thickness. The analytical plasma potentials, calculated from the experimental values are compared with the simulation results, show good agreement. It is suggested that under low biased voltage and high ICP power conditions, such as in the atomic layer etching process, the small ground surface affects the potential structure in the chamber.

Influence of the Refrigerant on the Performance of a Heat Pump with Gas Bearings

Heat pumps have become a potential technology for future thermal management systems in space. However, conventional heat pumps lubricated with oil are currently unfeasible due to the difficulty separating oil in microgravity environments. The oil-refrigerant mixture reduces the heat transfer capacity of heat exchangers, and insufficient separation can damage the compressor. This paper proposes a new heat pump with gas bearings (HPGB) that combines a centrifugal compressor with externally pressurized gas bearings to solve lubrication problems. A numerical model is established to compare performance of the HPGB system with different refrigerants. The results show that the coefficient of performance (COP) of the HPGB system is slightly smaller than those of conventional heat pumps, but higher than those of heat pumps with the impact of an oil concentration of 5%, when evaporator power is 30 kW. The HPGB system is more suitable for high-power conditions because of the higher COP. Ammonia is the best choice for the HPGB system under high-power conditions (above 80 kW). R134a is the best choice under middle-power conditions (from 25 kW up to 80 kW). R1234yf is more suitable with the maximum COP of 2.88 under low-power conditions (below 25 kW).

I am entitled to it! Social power and context modulate disadvantageous inequity aversion

Previous research consistently indicated that social power influences one's fairness consideration. However, it is unclear how social power and context jointly affect inequity aversion and whether these processes would be manifested in brain activities. In this study, participants were randomly assigned into either high or low power condition and then took part in a modified ultimatum game (UG) as responders in both gain and loss contexts, with their event-related potentials (ERPs) recorded. Behavioral results showed that powerful participants were more likely to reject unfair offers in both contexts compared with powerless ones. In addition, powerful participants showed a more negative feedback-related negativity (FRN) loss-win difference wave (d-FRN) upon presentation of proposed offers compared with powerless participants only in the gain context. Interestingly, in a later time window, differences of P300 responses to proposed offers were modulated by social power in both gain and loss contexts. These results suggested that powerful people were more sensitive to fairness levels and FRN may manifest fairness consideration in a gain context, but not in a loss context. Meanwhile, P300 is sensitive to fairness considerations in both gain and loss contexts.

Porous Au/AAO: A simple and feasible SERS substrate for dynamic monitoring and mechanism analysis of DNA oxidation

Herein, a simple strategy was proposed to acquire an orderly and controllable periodic structure. Firstly, the optimal parameters of porous anodic aluminum oxide (AAO) were screened out by FDTD solutions. Combined with magnetron sputtering of gold nano-film, the Au/AAO SERS substrate was thus fabricated. The enhancement factor (EF) was calculated to be 4.87 × 106, and SERS spectra with good reproducibility were also acquired. The oxidization process of plasmid DNA was thus monitored under the conditions of low detection power and short integration time. Fenton's reagent was used as oxidizing reagent, and Na2SO4 was applied for the internal standard in SERS analysis. The changes of I657/I998, I723/I998, I1587/I998, I1648/I998 were studied over time. DNA oxidation product 8-OHdG was also detected in this process. Then the relationship between the relative peak intensity ratios and the base structure change in DNA was established. The conclusions of SERS spectral analysis were verified by agarosegelelectrophoresis, DNA oxidative damage gel detection and colorimetric detection of 8-OHdG. The mechanism analysis of DNA oxidation process was thus studied. The simple and feasible detection strategy proposed could extend the application of SERS technology in the process monitoring of photosensitive or other unstable biological samples.

Numerical analysis of key structural parameters of ejector for PEMFC system under low power conditions

In this study, a three-dimensional numerical model of an ejector is established, which is based on a 40 W power proton exchange membrane fuel cell (PEMFC) system. Computational Fluid Dynamics (CFD) technique is used to analyze the ejector in low power condition. The effects of two key structural parameters (distance from the mixing chamber to the nozzle and the mixing chamber diameter) on the ejector performance at different currents are investigated. It is found that ejector entrainment ratio changes slightly with the distance from mixing chamber to nozzle. The ejector entrainment ratio increases first and then decreases with the mixing chamber diameter. Moreover, with the increase of mixing chamber diameter, the turbulent kinetic energy and turbulent dissipation rate decrease obviously.

Design of a CMOS memristor emulator-based, self-adaptive spiking analog-to-digital data conversion as the lowest level of a self-x hierarchy

Abstract. The number of sensors used in modern devices is rapidly increasing, and the interaction with sensors demands analog-to-digital data conversion (ADC). A conventional ADC in leading-edge technologies faces many issues due to signal swings, manufacturing deviations, noise, etc. Designers of ADCs are moving to the time domain and digital designs techniques to deal with these issues. This work pursues a novel self-adaptive spiking neural ADC (SN-ADC) design with promising features, e.g., technology scaling issues, low-voltage operation, low power, and noise-robust conditioning. The SN-ADC uses spike time to carry the information. Therefore, it can be effectively translated to aggressive new technologies to implement reliable advanced sensory electronic systems. The SN-ADC supports self-x (self-calibration, self-optimization, and self-healing) and machine learning required for the internet of things (IoT) and Industry 4.0. We have designed the main part of SN-ADC, which is an adaptive spike-to-digital converter (ASDC). The ASDC is based on a self-adaptive complementary metal–oxide–semiconductor (CMOS) memristor. It mimics the functionality of biological synapses, long-term plasticity, and short-term plasticity. The key advantage of our design is the entirely local unsupervised adaptation scheme. The adaptation scheme consists of two hierarchical layers; the first layer is self-adapted, and the second layer is manually treated in this work. In our previous work, the adaptation process is based on 96 variables. Therefore, it requires considerable adaptation time to correct the synapses' weight. This paper proposes a novel self-adaptive scheme to reduce the number of variables to only four and has better adaptation capability with less delay time than our previous implementation. The maximum adaptation times of our previous work and this work are 15 h and 27 min vs. 1 min and 47.3 s. The current winner-take-all (WTA) circuits have issues, a high-cost design, and no identifying the close spikes. Therefore, a novel WTA circuit with memory is proposed. It used 352 transistors for 16 inputs and can process spikes with a minimum time difference of 3 ns. The ASDC has been tested under static and dynamic variations. The nominal values of the SN-ADC parameters' number of missing codes (NOMCs), integral non-linearity (INL), and differential non-linearity (DNL) are no missing code, 0.4 and 0.22 LSB, respectively, where LSB stands for the least significant bit. However, these values are degraded due to the dynamic and static deviation with maximum simulated change equal to 0.88 and 4 LSB and 6 codes for DNL, INL, and NOMC, respectively. The adaptation resets the SN-ADC parameters to the nominal values. The proposed ASDC is designed using X-FAB 0.35 µm CMOS technology and Cadence tools.

Thermal-hydraulic stability investigations of once through helically coiled steam generators for SMR applications

Once-through steam generators with helically-coiled tubes (OTSG-HC) are susceptible to density wave instability phenomena. In order to investigate the stability performance of the CAREM-25 OTSG-HC, a new stability model is presented. Such a model being linear and strictly non-diffusive is able to represent arbitrary heat flux profiles, which is essential to study realistic cases. The OTSG-HC tubes are modeled by three different regions representing the liquid zone, the boiling zone, and the superheated vapor zone. Moreover, the coolant from the primary side is coupled with a model representing the phenomena present in CAREM-25. A convenient parameter space for stability representation is found and used to characterize the CAREM-25 OTSG-HC stability performance.In this work, special attention is paid to the calculation of the friction pressure losses in the coolant flowing through the helically coiled tubes. For this reason, a best estimate correlation is implemented and used in the model together with a sophisticated axial power profile model which allows representing realistic boundary conditions. As a result, it is confirmed the crucial importance of correctly representing the axial power profile transferred in the helically coiled tubes. In addition, it is found the commonly used uniform axial power profile leads to non-conservative stability predictions particularly at low power conditions. The latter is explained by the underestimation of the boiling and superheating lengths, which is proved to have a destabilizing effect.Stability maps are presented in terms of the transferred power and the primary coolant operational pressure, i.e. QSG-PPri plane. It is observed that when modeling realistic power profiles, the less stable operational condition of the OTSG-HC is found at very low powers, for all analyzed range of primary pressures. In addition, a weak stability dependence of the OTSG-HC with the pressure of the primary side is observed. Finally, the system is stabilized in the region of interest and its stability performance quantified.